This invention relates to a web cutoff and transfer apparatus and particularly to such apparatus for cutting and transfer of a moving web from a winding roll to a winding core unit.
In the processing of paper, film and like elements, a web of an indefinite length is often provided on a supply roll and rewound into one or more rewound rolls. The rewind apparatus is preferably constructed to maintain a continuous uninterrupted winding of the new rolls, including a cutoff and transfer mechanism for automatically cutting the web and transfering of the web from the end of rewound roll to a core means for the next rewound roll to be formed. Highly developed apparatus is commercially available for rewinding of paper, film and the like. A widely used cutoff and transfer apparatus includes a knife member mounted transversely of the web and suitably operated to move through the web. A cutter and transfer bar is provided to the opposite side of the web at the cutoff point. An air bar may be used to create a blast of air on the cut web to firmly support the web against the knife for rapid clean cutting and for promoting movement of the web onto the new core unit. Guide members are often also provided for guiding of the free end of the web onto the new core unit to promote a smooth wrapping of the web onto the core, after which it is tightly wound to assure a smooth, compact winding of the web into a roll.
In certain applications, different sized core units are used depending upon a particular winding specification. The diameter of the final wound roll may also vary from application to application. Generally, the cutoff blade and the cooperating cutting bar are desirably oriented in the same predesigned orientation at the moment of cutting the web. This is important not only to provide a smooth severing of the web but to properly locate the free end of the web immediately adjacent the core for movement onto the new core to initiate the new wrap. Further, the free end of the web should be placed on the core as a flat member, and essentially with a zero fold back of the free end. In many cutoff apparatus, the high speed movement of the web tends to cause the free end of the web to fold back on itself as it is being driven downwardly into the guides and onto the new core means. The fold back even where unacceptable is desirably minimized to produce a smooth, even roll.
In order to effect a very rapid and effective transfer with webs moving at high speed through the processing line, the knife must be accurately located and actuated in precise and rapid time relation to provide the desired repeatable and optimum cutting of the web.